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Old 16-05-2022, 01:18 PM
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spacezebra (Petra)
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On the topic of Dew Heaters

Hi all

I am interested in recommendations re dew heaters and how many straps they use.

I have a 102ED, guidescope and camera to keep dew free.

Will I need another external battery?? Hmmm?

Cheers Petra
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Old 16-05-2022, 04:58 PM
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Think of how much battery you need and double it..Heating and cooling draws a lot of current..but you find out the numbers..say all up you find you draw 5 amps and you run for 5 hours your consumption is approx 25 amp which means you need a 100 amp hour battery so you do not discharge past 25%.
But that is a maxed out situation whereas in reality you may not need everything running full on...But My advice in the first sentence is worthwhilecthinking about...we all do the numbers and the result may be out of touch with reality...when it is cold the numbers go down hill...some folk claim they get by with old car batteries..well good for them but my experience gained from living in the bush on 12 vlts causes me to make the statement in the first sentence...batteries are best pampered which means if you can only discharge them 10 percent that is great...that's lead acid. ..100 to 120 amp battery is a minimum in my view.
If you are serious have a small genny (800 watt) and charger in the car boot ...no power all the fancy gear ain't worth zip..but make a list of what each item draws then get a battery four times that number as a reasonable safe approach.
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Old 17-05-2022, 09:50 AM
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seeker372011 (Narayan)

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If you choose an ASIAIR you can run dew heaters and the imaging camera off its power outputs. Not your mount though, wouldn’t recommend that.

I had a Kendrick’s dew controller and dew strips but the controller is not necessary anymore with the ASIAIR

Still use the controller if using a pC/ mini pc

Dew bands from proastroz. The bands are a bit stiff but seem to do the job

One for scope one for guide scope seems pretty adequate
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Old 17-05-2022, 10:47 AM
Drac0 (Mark)
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Recently changed & added dew heaters and as Alex says, they are power hungry things. I have been running everything off 40AH of batteries without a problem but now I don't have the power for a full night - and I haven't added a cooled camera yet. I need to connect the charger halfway through. I run 2 or 3 dew heaters - scope, guide & DSLR camera lens when I piggyback. So upgrading to a 100AH battery. Lithium is good if you can afford one - lighter weight, larger possible draw down - but an AGM is fine.
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Old 17-05-2022, 11:53 AM
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spacezebra (Petra)
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Thank you all

Keep the advice coming...

Cheers Petra
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Old 17-05-2022, 01:26 PM
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OzEclipse (Joe Cali)
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Before spending big $ on generators and high power heaters, I'd recommend you try low power USB style heater wrapped around the lens hood but with some closed cell foam as insulation wrapped around the outside of that. eg. yoga mat material. These consume only about 2-3 watts each. 5A @ 12V is 60W and sounds like way too much heat to me. It obviously depends upon your local dew/fog conditions.

Try at first, buying just one of these and mount on your biggest lens with some insulation around the outside:-

It will probably work fine. If it doesn't do the job on your big lens, no money wasted, because it definitely will take care of your finder and/or a small guide scope.

You can run 3 of these plus a scope for a whole night off a small car battery. Check the power consumption of your mounting. My mount tracks at 1A, slews at 3A. I bought a 40 AH battery in 2015. It's still going strong 7 years and hundreds of recharges later. My three USB heaters draw 2W each, 0.5A total for three heaters. When photographing, typically I am not repeatedly slewing. So the total current draw is 1A (mount) + 0.5A (3xheaters) = 1.5A. Over 8hrs, that's about 12AH which the 40AH battery handles easily. I am not powering a cooled camera which can easily add 3A to the consumption.

This Century battery is 40AH, weighs 10kg, has a carry handle, and costs $170:-

If you are a power lifter, then consider a bigger battery. I prefer the smaller lighter batteries even though they only get me through one night before needing recharging. You will also need multiple 12V/USB supplies, one per heater or a USB hub with sufficient power for all the heaters, plus enough accessory cigarette sockets to power everything. I built my own power hub (photo) The USB PCB's cost $1 ea, the box, and cigarette lighter plug and the RCA jack panel about $15 in total. The cable was recycled from a household fan that was dead.

You will also need to buy a car battery charger.

In addition to 3 x USB, my box includes the 4 x RCA panel which is supplied by a separate buck/boost DC-DC converter. So I can dial in any voltage from 1.5V-35V to these jacks. They are currently set at a low voltage 3.5v for some home made heated camera lens hoods I have that are fitted with RCA connectors.

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